How much oxygen can be obtained by decomposing 15.8 g of potassium permanganate?

Let us write the reaction equation for the thermal decomposition of potassium permanganate:

2KMnO4 (t) = K2MnO4 + MnO2 + O2 ↑

Find the amount of potassium permanganate substance:

v (KMnO4) = m (KMnO4) / M (KMnO4) = 15.8 / 158 = 0.1 (mol).

According to the reaction equation, 1 mol of O2 is formed from 2 mol of KMnO4, therefore:

v (O2) = v (KMnO4) / 2 = 0.1 / 2 = 0.05 (mol).

Thus, the mass of oxygen that can be obtained is:

m (O2) = v (O2) * M (O2) = 0.05 * 32 = 1.6 (g).

Answer: 1.6 g.